There are tons of MBC5 flash cartridges out there, but all need you to salvage a MBC5 from an original cartridge. But luckily, MBC5 can be implemented with CPLD fair easily, so here it is.
Details
A simple game boy flash cartridge supports MBC1\5 games.
Source files can be found in the GitHub repository.
I am able to read out the Flash ID and CFI table now with the modified GB cart flasher!
I am using a MX29LV640 in 8bit mode (since native 8 bit flashes are hard to find or too expansive nowadays). It turns out that though 8bit mode is enabled (means an additional A0 bit), the device is still expecting the address for things like CFI appears on the original 16bit mode address bus which is A[x:1] instead of A[x:0] for the 8bit mode address bus. And I also had some soldering issue, took me several days to debug and find out what it going on. But now it is working! (As you can see, 51 52 59 represents "QRY" which is the start of the CFI table, and other things well match the datasheet)
the usb is attached to a 64 pin samd21. the pins are directly passed through too the ROM and ram as well as the header. to download games via usb and have direct controll over the header and ROM from fw.
Looking, good. I've been working on one as well. I need to finish it. If your interested checkout my site. Haven't had time to put it up on hackaday yet.
Any plans to sell this, through Tindie maybe?